Nickel disulfide / cobalt disulfide / tin disulfide nanocube material, preparation method and application thereof, and rechargeable battery

Abstract

The invention provides a nickel disulfide / cobalt disulfide / tin disulfide nanocube material, a preparation method and application thereof, and a rechargeable battery. The preparation method comprises the following steps: preparing a nanocube precursor through a room temperature aging method, vulcanizing and converting the nanocube precursor into a three-dimensional cubic material NiS2 / CoS2, and growing a SnS2 sheet layer on the cubic surface through a hydrothermal method to obtain a NiS2 / CoS2 / SnS2 composite material. Compared with the prior art, the cycle stability, the service life and the battery capacity are greatly improved by the product composition and the multi-crystal face structure, the three-dimensional structure design can bear large-current long circulation, the loss of active substances in the charging and discharging process is reduced, the volume change in the charging and discharging process is buffered, and the service life of the battery is prolonged. And the falling of the active material in the cycle process is reduced, sodium modification / sodium removal in the reaction process is facilitated, and the material has the advantages of good cycle performance, high energy density and the like when being applied to the sodium ion battery negative electrode material.

Description

Technical Field

[0001] This invention belongs to the field of rechargeable battery technology, specifically relating to a nickel disulfide / cobalt disulfide / tin disulfide nanocube material, its preparation method and application, and rechargeable batteries. The prepared ternary metal sulfide NiS2 / CoS2 / SnS2 is used as a negative electrode material for sodium-ion batteries. Background Technology

[0002] With ever-increasing energy demand, rechargeable batteries have become an indispensable part of energy storage systems. Lithium-ion (Li-ion) batteries are widely used in various portable products and new energy vehicles due to their high energy density and long cycle life. However, the continued growth in market demand and the shortage of lithium resources have prompted the development of more cost-effective batteries. Sodium (Na) is more abundant in the Earth's crust than lithium, and the extraction and purification costs of sodium are also lower than those of lithium. In addition, sodium and lithium have similar chemical properties, making sodium-ion batteries a strong alternative to lithium-ion batteries. Sodium-ion batteries (SIBs) are becoming an important complement to lithium-ion batteries (LIBs) thanks to their extensive energy storage capabilities based on the natural abundance and environmental friendliness of sodium resources.

[0003] Monometallic chalcogenides have been extensively studied and explored as anode materials for sodium-ion batteries. Compared with monometallic chalcogenides, multi-metallic chalcogenides exhibit extraordinary improvements in electrochemical performance, but only a very small number of ternary metal chalcogenides have been studied for use in sodium-ion batteries. Ternary metal chalcogenide-based sodium-ion battery anode materials have shown good electrochemical performance and should be explored as a promising sodium-ion anode material. Since ternary metal chalcogenides can be combined with a wide variety of metals or phases, and can be combined in many novel structures, developing other ternary metal chalcogenide combinations and using them as high-performance anode materials for SIBs has broad application prospects.

[0004] However, ternary metal chalcogenide materials used in sodium-ion batteries inevitably face the problem of relatively low performance. Summary of the Invention

[0005] The purpose of this invention is to provide a nickel disulfide / cobalt disulfide / tin disulfide nanocube material and its preparation method. First, a NiCo-PBA precursor is prepared, which is then sulfided to obtain a NiS2 / CoS2 composite material. Then, a SnS2 coating is grown on the outer layer to obtain the nickel disulfide / cobalt disulfide / tin disulfide nanocube material (NiS2 / CoS2 / SnS2 composite material).

[0006] Another objective of this invention is to provide an application of nickel disulfide / cobalt disulfide / tin disulfide nanocube materials, specifically for the preparation of sodium-ion battery anodes using these active materials.

[0007] The final objective of this invention is to provide a rechargeable battery prepared using the above-mentioned sodium-ion battery negative electrode.

[0008] The specific technical solution of this invention is as follows:

[0009] This invention provides a method for preparing nickel disulfide / cobalt disulfide / tin disulfide nanocube materials, comprising the following steps:

[0010] 1) Preparation of NiCo-PBA precursor;

[0011] 2) The NiCo-PBA precursor was vulcanized to obtain the NiS2 / CoS2 composite material;

[0012] 3) A SnS2 coating is grown on the outside of the NiS2 / CoS2 composite material.

[0013] In step 1), the method for preparing the NiCo-PBA precursor is as follows:

[0014] The organic ligand and nickel source were dispersed in a solvent and stirred to form a homogeneous solution A; the cobalt source was dispersed in a solvent and stirred to form a homogeneous solution B. Solution B was quickly poured into solution A and stirred. The resulting mixed solution was aged at room temperature to obtain the NiCo-PBA precursor.

[0015] In step 1), the molar ratio of the organic ligand, nickel source, and cobalt source is 2.2-2.5:1.5:1, preferably 2.25:1.5:1; the organic ligand is trisodium citrate trihydrate (C6H5Na3O7·3H2O); the nickel source is a soluble nickel source, preferably Ni(NO3)2·6H2O; the cobalt source is a soluble cobalt source, preferably K3[Co(CN)6]; the solvent used in solutions A and B is deionized water; preferably, the concentration of the organic ligand in the mixed solution is... The concentration of nickel source in the mixed solution is 0.022-0.025 mol / L, preferably 0.0225 mol / L; the concentration of nickel source in the mixed solution is 0.014-0.016 mol / L, preferably 0.015 mol / L; the concentration in the mixed solution is 0.009-0.011 mol / L, preferably 0.01 mol / L; the aging time at room temperature is 24 h; after aging at room temperature, the solution is washed 3-4 times with water and 1-2 times with ethanol, centrifuged, and dried at 60℃ for 8 h.

[0016] The prepared NiCo-PBA precursor is a nanocube with a size of 150-250 nm.

[0017] Preferably, the method for preparing the NiCo-PBA precursor is as follows: 11.25 mmol of C6H5Na3O7·3H2O and 7.5 mmol of Ni(NO3)2·6H2O are dispersed in 250 mL of deionized water and stirred vigorously to form solution A. 4.99 mol of K3[Co(CN)6] is dispersed in 250 mL of deionized water and stirred vigorously to form solution B. Solution B is quickly poured into solution A, stirred for 10 min, aged at room temperature for 24 h, washed, centrifuged and dried to obtain the product, the NiCo-PBA nanocube precursor.

[0018] In step 2), the sulfidation refers to mixing the NiCo-PBA precursor and sulfur powder and calcining them under a protective atmosphere; preferably, calcination is carried out in a tube furnace; the protective atmosphere is pure argon; the mass ratio of the NiCo-PBA precursor to sulfur powder is 1:10, and the calcination conditions are 400°C for 2 hours.

[0019] Step 3) Specifically, the NiS2 / CoS2 composite material and the sulfur source are dispersed in a solvent and mixed to obtain solution C; the tin source is dispersed in a solvent and stirred to form a uniform solution D; solution D is poured into solution C, and the resulting mixed solution undergoes a solvothermal reaction to obtain nickel disulfide / cobalt disulfide / tin disulfide nanocube material (NiS2 / CoS2 / SnS2).

[0020] In step 3), the mass ratio of the NiS2 / CoS2 composite material to the tin source is 1:2; the mass ratio of the sulfur source to the tin source is 1:2-4, preferably 1:2; the sulfur source is thioacetamide (TAA), and the tin source is a soluble tin source, preferably SnCl4·5H2O; the concentration of the sulfur source in the mixed solution is 0.0106-0.020 mol / L, preferably 0.019 mol / L; the concentration of the tin source in the mixed solution is 0.008-0.010 mol / L, preferably 0.0082 mol / L; the solvent used in solutions D and C is anhydrous ethanol; the solvothermal reaction is carried out at 150-170℃ for 12 hours, preferably at 160℃ for 12 hours; after the solvothermal reaction, the mixture is washed 3-4 times with water and 1-2 times with ethanol, centrifuged, and dried at 60℃ for 8 hours.

[0021] The nickel disulfide / cobalt disulfide / tin disulfide nanocube material prepared in step 3) has a sheet-like SnS2 coating on its surface with a size of 500-750 nm.

[0022] Preferably, step 3) specifically involves: dispersing 0.05g of NiS2 / CoS2 composite material and 0.05g of TAA in 20mL of anhydrous ethanol and sonicating for 10min to form solution C; dispersing 0.10g of SnCl4·5H2O in 15mL of anhydrous ethanol and stirring to form solution D; pouring solution D into solution C and stirring for 10min; then performing a solvothermal reaction at 160℃ for 12h; washing with water 3-4 times and ethanol 1-2 times; centrifuging; and drying at 60℃ for 8h to obtain NiS2 / CoS2 / SnS2.

[0023] The initial NiCo-PBA and sulfur powder formed in this invention are calcined in argon to generate NiS2 / CoS2. Step 3) involves the synthesis of nanocube NiS2 / CoS2 / SnS2, which is the process of SnS2 growing on the surface of the NiS2 / CoS2 cube. The composite cubic material formed by NiS2 and CoS2 has a large specific surface area and abundant surface defects. These defects and surface atoms can serve as nucleation sites for SnS2 growth. Simultaneously, there are chemical bonds or strong interactions between the Sn and S atoms in SnS2 and the atoms on the NiS2 / CoS2 surface. This interaction allows SnS2 to adsorb and gradually grow on the surface of the composite cubic material. Furthermore, the structure of the composite cubic material can spatially confine and template the growth of SnS2. The three-dimensional cubic structure of the NiS2 / CoS2 composite cubic material restricts SnS2 growth by these channels or crystal planes, causing it to grow along specific directions and planes, which is beneficial for forming a sheet-like structure on the surface of the composite cubic material.

[0024] In the preparation method of this invention, the effect of tin source concentration is as follows: SnCl4 provides tin ions, which are the key raw material for the formation of SnS2. At lower concentrations, Sn... 4+ Insufficient supply leads to a low number of SnS2 nuclei, slow growth, and potentially small, unevenly thick lamellar structures. When the SnCl4 concentration is too high, the high concentration of tin ions in the solution causes the nucleation rate of SnS2 to far exceed the growth rate, resulting in the simultaneous formation of numerous crystal nuclei. This results in small SnS2 particles that are difficult to grow into large lamellar structures. Higher concentrations of SnCl4 may also alter the growth orientation of SnS2 crystals. This is because during crystal growth, Sn... 4+ The concentration distribution of sulfur affects the formation and growth direction of SnS2 nuclei, causing SnS2 to grow no longer along the direction that favors the formation of lamellar structures, but instead potentially along other crystal planes, thus altering the morphology of the material. The effect of sulfur source concentration: TAA is the main source of sulfur in the reaction. At lower concentrations, the provided sulfur... 2-Insufficient concentration will result in a slower growth rate of SnS2, potentially leading to thinner, discontinuous SnS2 sheets, or failure to completely cover the surface of the NiS2 / CoS2 composite cubic material. Excessive concentration will result in... 2- Excessive amounts of TAA will increase the nucleation sites of SnS2, leading to excessively rapid growth and potentially smaller SnS2 crystals with severe aggregation, making it difficult to form a regular lamellar structure. Furthermore, TAA undergoes hydrolysis and other reactions in solution, and its concentration changes affect the chemical environment of the solution, including its acidity and alkalinity. For example, the alkaline substances produced by TAA hydrolysis will affect the pH of the solution, thus impacting the SnS2 crystal structure. 4+ With S 2- The combination mode and reaction rate of SnS2 are important factors. When the pH value is unsuitable, other tin-containing compounds may be generated, or the growth of SnS2 may proceed along different crystal planes, thus changing its morphology. Therefore, this invention requires reasonable control of the amounts of SnCl4·5H2O and TAA. Furthermore, the temperature of the solvothermal reaction also affects the morphology. At lower temperatures, the reaction rate is slow, the ion diffusion rate is also slow, and the nucleation and growth rates of SnS2 are both low, potentially resulting in smaller crystals and incomplete development of the lamellar structure. Conversely, at excessively high temperatures, the reaction rate is too fast, and ions rapidly combine to form SnS2, resulting in a large number of nuclei but a short growth time, easily forming small particles and making it difficult to grow into large lamellar structures. Only within a suitable temperature range, with a moderate reaction rate, is it beneficial for SnS2 to grow slowly along specific crystal planes, thus forming a more regular lamellar structure. Changes in solvothermal temperature affect the solubility of reactants and products. As temperature increases, the solubility of most substances increases, the ion concentration in the solution increases, and the supersaturation changes. When the temperature is low, the solubility of Sn in the solution... 4+ With S 2- The low supersaturation of SnS2 results in a weak nucleation driving force, which is unfavorable for the large-scale nucleation and growth of SnS2. As the temperature increases, the supersaturation gradually increases, and after reaching a certain level, SnS2 begins to nucleate and grow. However, if the temperature is too high, the supersaturation may be too large, leading to the simultaneous formation of a large number of crystal nuclei and inhibiting the growth of crystals along the lamellar direction. Therefore, this invention controls a suitable solvothermal reaction temperature.

[0025] The present invention provides a nickel disulfide / cobalt disulfide / tin disulfide nanocube material, which is prepared by the above method. SnS2 nanosheet coating is grown on the surface of a three-dimensional cubic NiS2 / CoS2 composite material to obtain NiS2 / CoS2 / SnS2 nanocube material with a size of 500-750nm, which greatly improves cycle stability, service life and battery capacity.

[0026] This invention provides an application of nickel disulfide / cobalt disulfide / tin disulfide nanocube material, which is used as an active material to prepare a sodium-ion battery anode.

[0027] The NiS2 / CoS2 / SnS2 cubic composite material and its polycrystalline structure prepared by this invention can greatly improve cycle stability, service life and battery capacity. Its three-dimensional structure design enables it to withstand high current and long cycle time, reduces the loss of active material during charge and discharge, buffers the volume change during charge and discharge, reduces the shedding of active material during cycle, and is beneficial to sodium formation / desodium formation during the reaction process. When applied to sodium-ion battery anode materials, this material has the advantages of good cycle performance and high energy density.

[0028] The present invention provides a rechargeable battery, which is prepared using the above-mentioned sodium-ion battery negative electrode.

[0029] Specifically: The nickel disulfide / cobalt disulfide / tin disulfide nanocube material prepared above is used as the active material. It is mixed with conductive carbon black and polyvinylidene fluoride in a ratio of 8:1:1 or 7:2:1, and then magnetically stirred for 6-8 hours to uniformly disperse it in N-methylpyrrolidone (NMP). The uniformly mixed slurry is coated onto copper foil using a coater and placed in a vacuum drying oven at 60-80°C for 12-24 hours. After drying, it is pressed into sheets using a tablet press and then cut into small circular electrode sheets using a cutting machine. The electrode sheets are assembled into button batteries in a glove box filled with high-purity argon gas and with water and oxygen values ​​≤0.01ppm. The electrolyte is NaPF6+DEGDME, the sodium sheet has a purity of Na≥99.99%, a thickness of 0.5mm, and is rolled and cut to the size of the electrode sheet.

[0030] The specific method for assembling the battery is as follows: After adding 1 drop of electrolyte to the positive electrode shell, place the electrode plate, then add 1 drop of electrolyte and place the glass fiber, add 3 drops of electrolyte to the glass fiber and place the sodium plate as the counter electrode, then place two pieces of nickel foam, add 4 drops of electrolyte, cover with the negative electrode shell, press and seal the battery with a hydraulic press, and let it stand for 6 to 12 hours.

[0031] The inventors discovered that transition metal chalcogenides (TMBs) are considered excellent anode materials for silicon carbide (SIB) batteries due to their stable operating voltage and high theoretical capacity. However, the significant volume change of TMBs during sodium ion insertion / extraction reduces battery capacity. Furthermore, TMB materials typically exhibit low electronic conductivity, leading to slow electron transport within the electrodes during charge / discharge, thus limiting charge / discharge efficiency and high-rate performance. This invention improves battery stability during cycling at high current densities by encapsulating three metal elements to form a three-dimensional cubic structure. The nickel disulfide / cobalt disulfide / tin disulfide material provided by this invention exhibits good cycle stability and high rate performance.

[0032] In this invention, the NiS2 / CoS2 / SnS2 nanocube material's nanocube structure provides a large specific surface area, facilitating the rapid insertion and extraction of sodium ions and reducing volume changes in the electrode material during charge and discharge. NiS2, CoS2, and SnS2 themselves possess certain electrical conductivity; the unique structure formed by their composite facilitates electron transport, reduces internal resistance, and improves charge / discharge efficiency and overall performance. The well-structured composite material enhances electronic conductivity and buffers internal stress, benefiting the electrochemical performance of SIBs. The composite material formed by the three metal sulfides synergistically enhances structural stability, inhibits pulverization and agglomeration, thereby improving cycle performance and extending battery life. Furthermore, the nanoscale size shortens the sodium ion diffusion path, and the synergistic effect between different components in the composite material optimizes electron conduction. This allows the material to maintain good electrochemical performance at different charge / discharge rates, enabling rapid response to high-current charge and discharge, meeting the demands for rapid charge and discharge in various application scenarios. Therefore, constructing a NiS2 / CoS2 / SnS2 polycrystalline structure can improve the volume expansion problem of metal sulfide materials in sodium-ion batteries, as well as enhance their reversible capacity and cycle stability. The multi-component synergistic effect of this invention promotes rapid charge transfer, resulting in excellent rate performance and cycle stability. The interfacial effect of the ternary metal sulfide can introduce an internal electric field to improve reaction kinetics, while providing abundant electrochemical reaction sites, thereby improving its reversible capacity and cycle stability. Therefore, combining the three-dimensional cubes of the NiS2 / CoS2 / SnS2 nanostructure is an effective strategy for achieving high-performance SIBs.

[0033] This invention develops anode materials with unique structures using a practical and direct SIB method. Electrode materials with nanostructures are promising candidates. Trimetallic sulfides, through the synergistic effect between multiple metals, add more active sites for redox reactions, thereby improving the electrochemical performance of the electrode. Employing trimetallic sulfide materials and effectively designing nanocube structures effectively mitigates volume expansion and prevents structural pulverization, thus preventing structural collapse of the electrode material.

[0034] Compared with existing technologies, this invention prepares nickel disulfide / cobalt disulfide / tin disulfide nanocubic materials. The synergistic effect between multiple metals provides more active sites for the reaction and improves conductivity, resulting in a significant improvement in sodium-ion battery performance. Furthermore, the three-dimensional structure creates a buffer space to mitigate volume changes. Benefiting from these advantages, the prepared NiS2 / CoS2 / SnS2 composite material exhibits high performance in 2Ag... -1 After 600 cycles at the current density, the display shows 559.5 mAh g. -1The high reversible capacity, high specific capacity, stable cycle performance, and robust rate performance demonstrate that NiS2 / CoS2 / SnS2 is an excellent and promising SIB anode material. Furthermore, this invention combines the three metal elements through a simple solvothermal reaction, which is easy to operate and utilizes inexpensive and readily available cobalt, nickel, and tin sources. The three-dimensional structure design significantly improves the battery's cycle stability, extends its lifespan, and increases and stabilizes its capacity. Attached Figure Description

[0035] Figure 1 SEM image of the NiCo-PBA precursor nanocube prepared in Example 1;

[0036] Figure 2 SEM image of the NiS2 / CoS2 three-dimensional nanocube prepared in Example 1;

[0037] Figure 3 SEM image of the NiS2 / CoS2 / SnS2 three-dimensional nanocube prepared in Example 1;

[0038] Figure 4 TEM image of the NiS2 / CoS2 / SnS2 three-dimensional nanocube prepared in Example 1;

[0039] Figure 5 XRD pattern of the NiS2 / CoS2 / SnS2 three-dimensional nanocube prepared in Example 1;

[0040] Figure 6 Mapping diagram of the NiS2 / CoS2 / SnS2 three-dimensional nanocubes prepared in Example 1;

[0041] Figure 7 HRTEM of the three-dimensional nanocube of NiS2 / CoS2 / SnS2 prepared in Example 1;

[0042] Figure 8 SEM image of the NiS2 / CoS2 / SnS2 composite material prepared in Example 2;

[0043] Figure 9 SEM image of the NiS2 / CoS2 / SnS2 composite material prepared in Example 3;

[0044] Figure 10 SEM image of the NiS2 / CoS2 / SnS2 composite material prepared in Example 4;

[0045] Figure 11 SEM image of the NiS2 / CoS2 / SnS2 composite material prepared in Example 5;

[0046] Figure 12SEM image of the NiS2 / CoS2 / SnS2 composite material prepared in Example 6;

[0047] Figure 13 SEM image of the NiS2 / CoS2 / SnS2 composite material prepared in Example 7;

[0048] Figure 14 SEM image of the NiS2 / CoS2 / SnS2 composite material prepared in Example 8;

[0049] Figure 15 SEM image of the NiS2 / CoS2 / SnS2 composite material prepared in Example 9;

[0050] Figure 16 SEM image of the NiS2 / CoS2 / SnS2 composite material prepared in Example 10;

[0051] Figure 17 The three-dimensional NiS2 / CoS2 / SnS2 nanocube material prepared in Example 1 was used as a sodium-ion battery anode material in 0.5 Ag. -1 Test graph of charge-discharge curves at current density;

[0052] Figure 18 The three-dimensional NiS2 / CoS2 / SnS2 nanocube material prepared in Example 1 was used as a sodium-ion battery anode material in 0.5 Ag. -1 Test graph of charge-discharge curves at current density;

[0053] Figure 19 The three-dimensional NiS2 / CoS2 / SnS2 nanocube material prepared in Example 1 was used as a sodium-ion battery anode material in 2Ag -1 Test graph of charge-discharge curves at current density;

[0054] Figure 20 The three-dimensional NiS2 / CoS2 / SnS2 nanocube material prepared in Example 1 was used as a sodium-ion battery anode material in 2Ag -1 Test graph of charge-discharge curves at current density;

[0055] Figure 21 The three-dimensional NiS2 / CoS2 / SnS2 nanocube material prepared in Example 1 was used as a lithium-ion battery anode material in 0.1, 0.5, 1, 3, and 5 Ag. -1 Cyclic performance test graph at current density. Detailed Implementation

[0056] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0057] Unless otherwise specified, all test materials and reagents used in the following examples are commercially available.

[0058] Unless otherwise specified in the embodiments, the techniques or conditions described in the literature in this field or in accordance with the product manual may be followed.

[0059] Example 1

[0060] A method for preparing nickel disulfide / cobalt disulfide / tin disulfide nanocube materials includes the following steps:

[0061] 1) Preparation of NiCo-PBA precursor:

[0062] Solution A was prepared by vigorously stirring 11.25 mmol of C6H5Na3O7·3H2O and 7.5 mmol of Ni(NO3)2·6H2O in 250 mL of deionized water. Solution B was prepared by vigorously stirring 4.99 mol of K3[Co(CN)6] in 250 mL of deionized water. Solution B was then rapidly poured into solution A, stirred for 10 min, aged at room temperature for 24 h, washed, and centrifuged to obtain the nanocube precursor. Its SEM image is shown below. Figure 1 As shown in the figure, it can be seen that it is a nanocube with a size of 200nm.

[0063] 2) NiS2 / CoS2 preparation:

[0064] 0.1 g of NiCo-PBA precursor and sulfur powder were weighed and placed in two separate ceramic boats at a mass ratio of 1:10. The boat containing the sulfur powder was placed upwind. The mixture was calcined in an argon atmosphere at 400℃ for 2 hours at a heating rate of 2℃ / min to obtain the product NiS2 / CoS2. Its SEM image is shown below. Figure 2 As shown in the figure, it can be seen that it is a nanocube but its surface is relatively smooth, and its size is 500nm.

[0065] 3) Preparation of NiS2 / CoS2 / SnS2:

[0066] 0.05 g NiS2 / CoS2 and 0.05 g TAA were dispersed in 20 mL of anhydrous ethanol and sonicated for 10 min to form solution C. 0.10 g SnCl4·5H2O was dispersed in 15 mL of anhydrous ethanol and stirred to form solution D. Solution D was poured into solution C and stirred for 10 min. The mixture was then subjected to a solvothermal reaction at 160 °C for 12 h. After washing four times with water and twice with ethanol, the mixture was centrifuged and dried at 60 °C for 8 h to obtain NiS2 / CoS2 / SnS2. Its SEM image is shown below. Figure 3 As shown in the SEM image, nanosheets are uniformly grown on the surface of a cubic block. Figure 4 The image shown is a TEM image of the NiS2 / CoS2 / SnS2 material. The TEM image also shows that the surface is uniformly grown with lamellar layers.

[0067] The XRD pattern of the NiS2 / CoS2 / SnS2 composite material obtained in this embodiment is shown below. Figure 5 As shown, the obtained product is NiS2 / CoS2 / SnS2. Figure 6 The diagram shows the mapping of the material, which indicates that the elements in the composite material are evenly distributed. Figure 7 This is the HRTEM image of the material.

[0068] Example 2 (as a comparison)

[0069] A method for preparing a nickel disulfide / cobalt disulfide / tin disulfide material includes the following steps:

[0070] 1) The preparation of the NiCo-PBA precursor is the same as in Example 1;

[0071] 2) The preparation of NiS2 / CoS2 is the same as in Example 1;

[0072] 3) Preparation of NiS2 / CoS2 / SnS2:

[0073] 0.05 g NiS2 / CoS2 and 0.025 g TAA were dispersed in 20 mL of anhydrous ethanol and sonicated for 10 min to form solution C. 0.10 g SnCl4·5H2O was dispersed in 15 mL of anhydrous ethanol and stirred to form solution D. Solution D was poured into solution C and stirred for 10 min. The reaction was then carried out at 160 °C for 12 h using a solvothermal method. The mixture was washed 4 times with water and 2 times with ethanol. After centrifugation, the mixture was dried at 60 °C for 8 h to obtain NiS2 / CoS2 / SnS2.

[0074] Its SEM image is as follows Figure 8 As shown in the figure, it has no obvious morphology. Lowering the TAA concentration resulted in a lower concentration providing S... 2-Insufficient growth will slow down the growth rate of SnS2, so it is rare to observe a complete lamellar coating on a cube, or even no lamellar coating may grow on the cube at all.

[0075] Example 3 (as a comparison)

[0076] A method for preparing a nickel disulfide / cobalt disulfide / tin disulfide material includes the following steps:

[0077] 1) The preparation of the NiCo-PBA precursor is the same as in Example 1;

[0078] 2) The preparation of NiS2 / CoS2 is the same as in Example 1;

[0079] 3) Preparation of NiS2 / CoS2 / SnS2:

[0080] 0.05 g NiS2 / CoS2 and 0.1 g TAA were dispersed in 20 mL of anhydrous ethanol and sonicated for 10 min to form solution C. 0.10 g SnCl4·5H2O was dispersed in 15 mL of anhydrous ethanol and stirred to form solution D. Solution D was poured into solution C and stirred for 10 min. The reaction was carried out at 160 °C for 12 h using a solvothermal method. The mixture was then washed three times with water and twice with ethanol. After centrifugation, the mixture was dried at 60 °C for 8 h to obtain NiS2 / CoS2 / SnS2.

[0081] Its SEM image is as follows Figure 9 As shown in the figure, it is an irregular cube. The TAA concentration is too high, S 2- Excessive amounts will increase the number of nucleation sites for SnS2, resulting in excessively rapid growth. This may lead to smaller SnS2 grains, severe agglomeration, and difficulty in forming a regular lamellar structure.

[0082] Example 4 (as a comparison)

[0083] A method for preparing a nickel disulfide / cobalt disulfide / tin disulfide material includes the following steps:

[0084] 1) The preparation of the NiCo-PBA precursor is the same as in Example 1;

[0085] 2) The preparation of NiS2 / CoS2 is the same as in Example 1;

[0086] 3) Preparation of NiS2 / CoS2 / SnS2:

[0087] 0.05 g NiS2 / CoS2 and 0.15 g TAA were dispersed in 20 mL of anhydrous ethanol and sonicated for 10 min to form solution C. 0.10 g SnCl4·5H2O was dispersed in 15 mL of anhydrous ethanol and stirred to form solution D. Solution D was poured into solution C and stirred for 10 min. The reaction was then carried out at 160 °C for 12 h using a solvothermal method. The mixture was washed 4 times with water and 1 time with ethanol, centrifuged, and dried at 60 °C for 8 h to obtain NiS2 / CoS2 / SnS2.

[0088] Its SEM image is as follows Figure 10 As shown in the figure, the product has an irregular shape. Similarly, due to the excessively high TAA concentration, S... 2- Excessive amounts of SnS2 will increase the number of nucleation sites and accelerate the growth rate, potentially resulting in smaller SnS2 grains, severe agglomeration, and difficulty in forming regular lamellar structures. Therefore, the products formed at this concentration will have irregular morphology.

[0089] Example 5 (as a comparison)

[0090] A method for preparing a nickel disulfide / cobalt disulfide / tin disulfide material includes the following steps:

[0091] 1) The preparation of the NiCo-PBA precursor is the same as in Example 1;

[0092] 2) The preparation of NiS2 / CoS2 is the same as in Example 1;

[0093] 3) Preparation of NiS2 / CoS2 / SnS2:

[0094] 0.05 g NiS2 / CoS2 and 0.05 g TAA were dispersed in 20 mL of anhydrous ethanol and sonicated for 10 min to form solution C. 0.050 g SnCl4·5H2O was dispersed in 15 mL of anhydrous ethanol and stirred to form solution D. Solution D was poured into solution C and stirred for 10 min. The reaction was carried out at 160 °C for 12 h under solvothermal conditions. The mixture was then washed 4 times with water and 2 times with ethanol. After centrifugation, the mixture was dried at 60 °C for 8 h to obtain NiS2 / CoS2 / SnS2.

[0095] Its SEM image is as follows Figure 11 As shown in the figure, the product consists of cubes of varying sizes, some with uneven, flake-like surfaces. When the tin ion concentration is low, Sn... 4+ Due to insufficient supply, SnS2 has a low nucleation rate, slow growth, and may form small, unevenly thick, sheet-like structures.

[0096] Example 6 (as a comparison)

[0097] A method for preparing a nickel disulfide / cobalt disulfide / tin disulfide material includes the following steps:

[0098] 1) The preparation of the NiCo-PBA precursor is the same as in Example 1;

[0099] 2) The preparation of NiS2 / CoS2 is the same as in Example 1;

[0100] 3) Preparation of NiS2 / CoS2 / SnS2:

[0101] 0.05 g NiS2 / CoS2 and 0.05 g TAA were dispersed in 20 mL of anhydrous ethanol and sonicated for 10 min to form solution C. 0.20 g SnCl4·5H2O was dispersed in 15 mL of anhydrous ethanol and stirred to form solution D. Solution D was poured into solution C and stirred for 10 min. The reaction was then carried out at 160 °C for 12 h using a solvothermal method. The mixture was washed 4 times with water and 2 times with ethanol, centrifuged, and dried at 60 °C for 8 h to obtain NiS2 / CoS2 / SnS2.

[0102] Its SEM image is as follows Figure 12 As shown in the figure, the product has an irregular morphology. When the SnCl4 concentration is too high, the tin ion concentration in the solution is too large, which will cause the nucleation rate of SnS2 to be much greater than the growth rate. A large number of crystal nuclei will be formed at the same time, resulting in the final SnS2 particles being small and difficult to grow into large plate-like structures.

[0103] Example 7 (as a comparison)

[0104] A method for preparing a nickel disulfide / cobalt disulfide / tin disulfide material includes the following steps:

[0105] 1) The preparation of the NiCo-PBA precursor is the same as in Example 1;

[0106] 2) The preparation of NiS2 / CoS2 is the same as in Example 1;

[0107] 3) Preparation of NiS2 / CoS2 / SnS2:

[0108] 0.05 g NiS2 / CoS2 and 0.05 g TAA were dispersed in 20 mL of anhydrous ethanol and sonicated for 10 min to form solution C. 0.30 g SnCl4·5H2O was dispersed in 15 mL of anhydrous ethanol and stirred to form solution D. Solution D was poured into solution C and stirred for 10 min. The reaction was carried out at 160 °C for 12 h under solvothermal conditions. The mixture was then washed 4 times with water and 2 times with ethanol. After centrifugation, the mixture was dried at 60 °C for 8 h to obtain NiS2 / CoS2 / SnS2.

[0109] Its SEM image is as follows Figure 13As shown in the figure, the product consists of cubes of varying sizes with agglomerated surfaces. Higher concentrations of SnCl4 may alter the growth orientation of SnS2 crystals. This is because during crystal growth, Sn... 4+ The concentration distribution of SnS2 can affect the formation and growth direction of SnS2 crystal nuclei, causing SnS2 to no longer grow along the direction that is conducive to the formation of lamellar structures, but may grow along other crystal planes, thereby changing the morphology of the material.

[0110] Example 8 (as a comparison)

[0111] A method for preparing a nickel disulfide / cobalt disulfide / tin disulfide material includes the following steps:

[0112] 1) The preparation of the NiCo-PBA precursor is the same as in Example 1;

[0113] 2) The preparation of NiS2 / CoS2 is the same as in Example 1;

[0114] 3) Preparation of NiS2 / CoS2 / SnS2:

[0115] 0.05 g NiS2 / CoS2 and 0.05 g TAA were dispersed in 20 mL of anhydrous ethanol and sonicated for 10 min to form solution C. 0.10 g SnCl4·5H2O was dispersed in 15 mL of anhydrous ethanol and stirred to form solution D. Solution D was poured into solution C and stirred for 10 min. The reaction was carried out at 100 °C for 12 h under solvothermal conditions. The mixture was then washed 4 times with water and 2 times with ethanol. After centrifugation, the mixture was dried at 60 °C for 8 h to obtain NiS2 / CoS2 / SnS2.

[0116] Its SEM image is as follows Figure 14 As shown in the figure, the product consists of cubical aggregates of varying sizes with lamellar surfaces. At lower temperatures, the reaction rate is slow, the ion diffusion rate is also slow, and the nucleation and growth rates of SnS2 are both low, which may result in smaller crystals and incomplete development of the lamellar structure.

[0117] Example 9 (as a comparison)

[0118] A method for preparing a nickel disulfide / cobalt disulfide / tin disulfide material includes the following steps:

[0119] 1) The preparation of the NiCo-PBA precursor is the same as in Example 1;

[0120] 2) The preparation of NiS2 / CoS2 is the same as in Example 1;

[0121] 3) Preparation of NiS2 / CoS2 / SnS2:

[0122] 0.05 g NiS2 / CoS2 and 0.05 g TAA were dispersed in 20 mL of anhydrous ethanol and sonicated for 10 min to form solution C. 0.10 g SnCl4·5H2O was dispersed in 15 mL of anhydrous ethanol and stirred to form solution D. Solution D was poured into solution C and stirred for 10 min. The reaction was carried out at 120 °C for 12 h under solvothermal conditions. The mixture was then washed three times with water and once with ethanol. After centrifugation, the mixture was dried at 60 °C for 8 h to obtain NiS2 / CoS2 / SnS2.

[0123] Its SEM image is as follows Figure 15 As shown in the figure, the product consists of cubes of varying sizes with lamellar aggregates on the surface. At lower temperatures, the reaction rate is slow, the ion diffusion rate is also slow, and the nucleation and growth rates of SnS2 are both low, which may result in smaller crystals and incomplete development of the lamellar structure, leading to changes in morphology.

[0124] Example 10 (as a comparison)

[0125] A method for preparing a nickel disulfide / cobalt disulfide / tin disulfide material includes the following steps:

[0126] 1) The preparation of the NiCo-PBA precursor is the same as in Example 1;

[0127] 2) The preparation of NiS2 / CoS2 is the same as in Example 1;

[0128] 3) Preparation of NiS2 / CoS2 / SnS2:

[0129] 0.05 g NiS2 / CoS2 and 0.05 g TAA were dispersed in 20 mL of anhydrous ethanol and sonicated for 10 min to form solution C. 0.10 g SnCl4·5H2O was dispersed in 15 mL of anhydrous ethanol and stirred to form solution D. Solution D was poured into solution C and stirred for 10 min. The reaction was then carried out at 140 °C for 12 h using a solvothermal method. The mixture was washed 4 times with water and 2 times with ethanol, centrifuged, and dried at 60 °C for 8 h to obtain NiS2 / CoS2 / SnS2.

[0130] Its SEM image is as follows Figure 16 As shown in the figure, the products are cubes of varying sizes. Some cubes have lamellar aggregates on their surface, while others lack long lamellar structures. At lower temperatures, the reaction rate is slower, and the ion diffusion rate is also slower. This results in lower nucleation and growth rates of SnS2, which may lead to smaller crystals, incomplete development of the lamellar structure, and altered morphology.

[0131] Example 11

[0132] An application of a nickel disulfide / cobalt disulfide / tin disulfide nanocube material is disclosed, which is used as an active material in the preparation of a sodium-ion battery anode, thereby enabling the fabrication of a sodium-ion rechargeable battery. Specifically:

[0133] The nickel sulfide / cobalt disulfide / tin disulfide nanocube material prepared in Example 1 was used as the active material. It was mixed with conductive carbon black and polyvinylidene fluoride in a ratio of 8:1:1 and then magnetically stirred for 8 hours to disperse it evenly in NMP. The uniformly mixed slurry was coated onto copper foil using a coater and placed in a vacuum drying oven at 80°C for 24 hours. After drying, it was pressed into sheets using a tablet press and then cut into small circular electrode sheets using a cutting machine. The electrode sheets were assembled into button batteries in a glove box filled with high-purity argon gas and with water and oxygen values ​​≤0.01ppm. The electrolyte was NaPF6+DEGDME, the sodium sheet purity was Na≥99.99%, the thickness was 0.5mm, and it was rolled and cut to the size of the electrode sheet.

[0134] The specific method for assembling the battery is as follows: Add one drop of electrolyte to the positive electrode shell, then place the electrode plate. Next, add one drop of electrolyte and place the glass fiber. Add three drops of electrolyte to the glass fiber and place a sodium sheet as the counter electrode. Then, place two pieces of nickel foam, add four more drops of electrolyte, cover with the negative electrode shell, and use a hydraulic press to press and seal the battery. Let it stand for 12 hours.

[0135] Specific testing process: After assembling the sodium-ion half-cell, set the steps on the Xinwei tester, first discharge with constant current to 0.01V, then charge with constant current to 3V, and repeat this cycle a certain number of times.

[0136] Then, the cycle performance and charge / discharge performance of the coin cell were tested at currents of 0.5A and 2A, and the results are as follows: Figure 17 , Figure 18 , Figure 19 , Figure 20 As shown in the figure, there is a relatively stable charge-discharge plateau at 0.5Ag. -1 After 400 cycles, it still has 734.06 mAh g. -1 The capacity coulombic efficiency is 99.77%; in 2Ag -1 After 600 cycles, it still has 559.51 mAh g. -1 The capacity has a coulombic efficiency of 99.80%. This is achieved at Ag values ​​of 0.1, 0.5, 1, 3, and 5. -1 The rate capability of the battery was tested at a current density of 21. As can be seen from Figure 21, the material has good rate performance and can withstand a large current.

[0137] This invention prepares a nano-cubic precursor through room temperature aging, which is then converted into a three-dimensional cubic material, NiS2 / CoS2, using a tube furnace. Further hydrothermal treatment is then used to grow SnS2 sheets on the cubic surface. The NiS2 / CoS2 / SnS2 composite material and its polycrystalline structure can significantly improve cycle stability, lifespan, and battery capacity. Its three-dimensional structure allows it to withstand high current and long-term cycling, reducing the loss of active material during charge and discharge, buffering volume changes during charge and discharge, reducing the shedding of active material during cycling, and facilitating sodium formation / desodium formation during the reaction process. This material, when applied as a negative electrode material in sodium-ion batteries, exhibits advantages such as good cycle performance and high energy density.

[0138] The above description of the embodiments is intended to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A method for preparing nickel disulfide / cobalt disulfide / tin disulfide nanocube materials, characterized in that, The preparation method includes the following steps: 1) Preparation of NiCo-PBA precursor; 2) The NiCo-PBA precursor was vulcanized to obtain the NiS2 / CoS2 composite material; 3) A SnS2 coating is grown on the outside of the NiS2 / CoS2 composite material.

2. The preparation method according to claim 1, characterized in that, In step 1), the method for preparing the NiCo-PBA precursor is as follows: The organic ligand and nickel source were dispersed in a solvent and stirred to form a homogeneous solution A; the cobalt source was dispersed in a solvent and stirred to form a homogeneous solution B. Solution B was quickly poured into solution A and stirred. The resulting mixed solution was aged at room temperature to obtain the NiCo-PBA precursor.

3. The preparation method according to claim 2, characterized in that, In step 1), the molar ratio of the organic ligand, nickel source and cobalt source is 2.2-2.5:1.5:

1.

4. The preparation method according to claim 2 or 3, characterized in that, In step 1), the organic ligand is trisodium citrate trihydrate; the cobalt source is K3[Co(CN)6].

5. The preparation method according to claim 1, characterized in that, Step 3) Specifically, the NiS2 / CoS2 composite material and the sulfur source are dispersed in a solvent and mixed to obtain solution C; the tin source is dispersed in a solvent and stirred to form a uniform solution D; solution D is poured into solution C; the resulting mixed solution undergoes a solvothermal reaction to obtain nickel disulfide / cobalt disulfide / tin disulfide nanocube materials.

6. The preparation method according to claim 5, characterized in that, In step 3), the concentration of the sulfur source in the mixed solution is 0.0106-0.020 mol / L; the concentration of the tin source in the mixed solution is 0.008-0.010 mol / L.

7. The preparation method according to claim 5 or 6, characterized in that, In step 3), the solvothermal reaction is carried out at 150-170℃ for 12 hours.

8. A nickel disulfide / cobalt disulfide / tin disulfide nanocubic material prepared by the preparation method according to any one of claims 1-7, characterized in that, The nickel sulfide / cobalt disulfide / tin disulfide nanocube material prepared by the method is a SnS2 coating grown on the surface of a three-dimensional cubic NiS2 / CoS2 composite material, with a size of 500-750 nm.

9. An application of the nickel disulfide / cobalt disulfide / tin disulfide nanocubic material according to claim 8, characterized in that, The nickel disulfide / cobalt disulfide / tin disulfide nanocube material is used to prepare the negative electrode of a sodium-ion battery.

10. A rechargeable battery, characterized in that, The rechargeable battery includes the sodium-ion battery negative electrode as described in claim 9.

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